Keyboard operated electrical switches



May 17, 1%6 F. M. LUND KEYBOARD OPERATED ELECTRICAL SWITCHES 2Sheets-Sheet 1 Filed May 29, 1962 INVENTOR. L926: [L BY 2 M6 1M,

NAN

May 17, 196

Filed May 29, 1962 F LUND KEYBOARD OPERATED ELECTRICAL SWITCHES 2 SheetsSheet 2 3,251,923 KEYBOARD OPERATED ELECTRICAL SWITCHES Frank M. Lund,Northbrook, Ill., assignor to Pratt, Read & Co.,' Incorporated,Ivoryton, Conn., a corporation of Connecticut Filed May 2% 1962, Ser.No. 198,670 8 Claims. (C1, 841.01)

In electronic musical instruments such as organs, pianos,

and accordions, it is conventional to provide means which activates aswitch upon depression of a selected key on the keyboard to complete anelectrical circuit between associated tone generators and mixing bussesso that given waveforms of a selected frequency can be coupled toelectroacoustical transducers to produce a desired musical effect. It isimportant that the keys and their associated switches operate with aminimum of manual pressure to provide a firm reliable electrical contactwithout generating objectionable mechanical and electrical noise.Because of the large number of circuits involved, it is also desirablethat the circuit making elements coacting with individual keys toprovide the switching be durable to insure operating life yet be simplein construction to form a compact unit which is economical to assembleand is readily accessible for maintenance.

It is therefore an object of the present invention to provide 'a keyswitch assembly for use with electronic musical instruments that isessentially free from noise during operation.

A further object is to provide a key switching arrangement for use withelectronic musical instruments which makes positive and reliableelectrical contact with associated mixing busses, and which incorporatesa construction that insures long operating life.

Another object is to provide a key switch assembly for coaction with amusical keyboard which is operable by a minimum of manual pressureapplied to individual playing keys.

Still another object is to provide an electrical key switch whichemploys a simple and compact circuit interconnection panel that can beeconomically fabricated and readily assembled with the coactingkeyboard.

A feature of the present invention is the provision of a keyboard havingpivotally mounted key assemblies and coacting lever arms adapted to movein an arcuate path upon activation of individual key assemblies. Aresilient insulating member forms a flexible tie-bar connected betweenone end of each lever arm and flexible coil springs to imparttranslational movement to the free ends thereof to make electricalcontact with stationary signal mixing busses, thereby completing anelectrical circuit between individual tone generators associated withselected key assemblies and the electroacoustical transducers of thesystem.

-A further feature ofthe invention is the provision of an organ keyswitch arrangement including a plurality of coil springs having a fixedend supported by a plated circuit panel and a free end coupled by aflexible insulating member to a key activated lever arm. The flexiblemember imparts translational movement to the free ends of the coilsprings upon arcuate movement of the lever arm by depression of selectedkeys to make electrical contact with mixing busses, and a plated oretched circuit wiring pattern interconnects the coil springs andisolation resistors disposed on the circuit panel to complete anelectrical circuit between selected tone generators and the audioamplifiers of the system.

Another feature is the provision, in a key switch arrangement of thetype described above, of a coating of resilient resistive material onthe mixing busses to provide noise deadening during the switchingoperation and to provide a predetermined resistance value in thecircuit.

A still further feature is the provision of a tie-rod molded fromresilient insulating material to couple the key activated lever arm tothe free ends of selected coil springs in the above-described switchingarrangement to provide positive, noiseless switch activation with aminimum of keyboard pressure.

Other objects, advantages and features of the invention will becomeapparent upon making reference to the following specification, claimsand drawings, in which:

FIG. 1 is a fragmentary perspective view of an organ keyboard chassisassembly incorporating thekey switching arrangement of the presentinvention;

FIG. 2 is a vertical sectional view of the keyboard chassis assembly ofFIG. 1, taken substantially along line 22;

FIG. 3 is a bottom plan view of the chassis assembly of FIG. 1;

FIG. 4 is a transverse section taken substantially along line 44 of FIG.2;

FIG. 5 is a vertical sectional view of the keyboard chassis assembly ofFIG. 1, illustrating a key in a depressed position, taken substantiallyalong line 55;

FIG. 6 is a plane view .of the plated circuit panel of the invention,illustrating a typical circuit configuration;

FIG. 7 is a fragmentary perspective of circuit panel showing analternate configuration of the means coupling the coil springs to thelever arms actuated by the key assemblies; and

FIG. 8 is a view of an alternate type of lever arm for use in theassembly of FIG. 1.

In practicing the present invention there is provided a generally flatchassis having an upstanding fulcrumforming wall on the rear marginaledge thereof and a plurality of upstanding fingers on the front marginaledge thereof. A plurality of elongated key assemblies are transverselydisposed between the two marginal edges, with the fulcrum-forming wallproviding pivotal points I for the key assemblies and the upstandingfingers cooperating with the key assemblies to provide up and downstops. Each key assembly is maintained in a normally up position by abiasing spring and may be depressed to the down position by applicationof suflicient manual pressure to overcome the bias thereby provided.Lever means associated with each key assembly include arms extendingabove and below the chassis through openings in the flat portion of thechassis, and are mounted to pivot about a horizontally disposed axislocated near the front marginal edge of the chassis. Extensions of thelever arms above the chassis include off-center portions which coactwith individual key assemblies to provide rotation of the levers andthus arcuate movement of the arms extending below the chassis within thelimits provided by the up and down stops as individual key assembliesare depressed.

A generally elongated insulating panel is provided below a flat portionof the chassis, coextensive with the key assemblies. The insulatingpanel contains plated or tilted circuit wiring patterns and associatedcircuit components for interconnection of individual tone generatorswith the audio amplifiers and the electroacoustical transducers of theassociated audio system. A plurality of signal mixing busses, whichfurther function as the fixed contacts for the switching arrangement,are supported from and extend the length of the insulating panel. Aplurality of resilient,

g the chassis assembly.

' pling portion of the insulating member imparts a transla tionalmovement to the free ends of the coil springs to thereby complete anelectrical circuit between associated coil springs and the mixingbusses. Release of manual pressure from the key assembly causes it to bebiased to its normal up position and the resilient coil springs returnto their pendent positions to open the electrical circuit.

In a typical electronic organ system isolation resistors are serieswired between selected coil springs and individual tone generators.Contact with the mixing busses completes the circuit between the tonegenerators and the audio amplifiers and acoustical transducers of thesys tem. A predetermined plate or etched circuit wiring pat terndisposed on the insulating panel interconnects isolation resistors, alsolocated on the panel, to selected coil springs so that depression ofindividual keys provides the necessary signal mixing to produce adesired musical effect. The plated or etched circuit wiring pattern andthe interconnecting isolation resistors may be disposed in a manner toprovide octave-to-octave coupling with the mixing busses, depending onthe complexity of the individual musical instrument with which the keyswitch arrangement is used. To further enhance noise free operation ofthe switching arrangement a pliable resistive material may be applied tothe mixing busses. This material may be selected to provide a fixed orvariable value of resistance between the coil springs and the busses, ormay be of substantially zero resistance.

Referring now to FIGS. 1 and 2 of the drawings, the keyboard assemblyincorporating the key switch arrangement of the present inventionincludes an elongated chassis member having a substantially flathorizontal portion 20. A plurality of key assemblies 12 are supported inlongitudinally spaced relation upon the chassis member 10 to form aconventional organ or accordion keyboard. Each key assembly comprises aleft or right hand white key piece 12a or 1212 or a black key piece 13,and an elongated channel-shaped arm 14a or 14b, the front portion ofwhich is overlaid by the key piece involved. Individual key pieces aresecured to channel-shaped arms 14a or 14b by a plurality of screws 15.The left hand white key piece 12a and the right hand white key piece 12bis shaped to extend part way around the front portion of black key piece13 in the usual manner.

Chassis member 10 is made of a single sheet metal stamping having a maingenerally horizontal rectangular panel section an upwardly projectingfulcrum-forming wall 22 extending for substantially the full length ofthe rear longitudinal margin, and downwardly projecting flange portion24 extending substantially the full length of the front longitudinalmargin. Downwardly projecting portion 24is provided with bracketed feet25 for front support and bracketed legs 27 provide rear support for Aseries of upwardly projecting longitudinally spaced fingers 28 extendupwardly from the horizontal upper marginal edge 29 of fulcrum formingwall 22. A plurality of slots 31 are provided in upper marginal edge 29of fulcrum forming wall 22. These slots are spaced apart at a distanceslightly greater than the longitudinal width of upwardly projectingfingers 28 and coincide with downwardly extending flanges 32 on arms 14aand 141).

A front member 35, containing a series of longitudinally spaced fingers36, is secured to the front longitudinal margin of rectangular panelsection 20. Fingers 36 have a portion struck parallel to horizontalsection 20 and are in transverse alignment with upwardly projectingfingers 28. A body of resilient flexible material 37, such as neoprenerubber or a suitable plastic material, generally rectangular incross-section and having a small aperture therein is secured to fingers36 in the manner shown. Referring more specifically to FIGS. 3 and 5,side flanges 32 of elongated arms 14a and 14b are provided with inwardlyprojecting lugs 38 on the bottom thereof, located directly above thehorizontal portion of fingers 36. Lugs 38 form horizontal abutmentshoulders at the bottom of elongated channels 14a and 14b to abutagainst the bottom portion of resilient stop member 37 to thereby limitthe upward movement of individual key assemblies, as is most clearlyshown in FIG. 2 wherein the key assembly including key piece 12a and arm14b is shown in its upmost position. Sufficient clearance is providedbetween the upper surface of flexible stop member 37 and the top ofelongated channels 14a and 14b to permit the necessary downward movementof the key unit involved. Thus, by abutment against lugs 38 when the keyassembly is in its upmost position and against the top of elongatedchannel-shaped arms 14a and 14b when the key assembly is in its downmostposition, flexible stop member 37 functions as both an upstop and adownstop for the key assembly.

Side flanges 32 of elongated channel-shaped arms 14a and 14b are furtherprovided with generally V-shaped notches 40. These notches are engagedwith slots 31 in the upper marginal edge 29 of fulcrum-forming wall 22to provide the fulcrum point for the key assemblies. Fingers 28 extendthrough a plurality of generally rectangular openings 41 in the uppersurface of arms 14a and 14b. Openings 41 have sufiicient width to justengage the longitudinal edges of fingers 28. This engagement, inconjunction with the engagement of notches 40 with slots 31 on fulcrumforming wall 22, prevent relative lateral movement betweenchannel-shaped arms 14a and 14b and the chassis member. When assembledfingers 28 pass through openings 41 and the apex of V-shaped notches 40engage'the bottom slots 31 thereby forming the fulcrum points whichpivotally support individual key assemblies. Sufficient clearance existsbetween the front and rear of fingers 28 and the front and rear ofopenings 41 so that the fingers do not touch the front and rear portionsof openings 41 for all positions of the key assembly. On the other hand,there is little or no clearance between the fingers 28 and the sides ofthe walls of openings 41, thus restraining lateral movement of the keyassemblies. Individual key assemblies are spring biased by tensionspring members 44 extending between spring anchoring lugs 45 and 46respectively, struck from the channel-shaped arms andfrorn the chassismember. The front ends of the keyiassemblies are thereby biasedupwardly, with the upward movement of each key assembly limited by stopmember 37 in abutment with lugs 38.

As has been previously mentioned, individual key pieces are secured tothe channel-shaped arms by screws 15. Each of channel shaped arms 14aand 14b have forward extending tongue portions 50 on the upper surface,

as best seen in FIG. 3. Each key piece is of a generally hollowconfiguration molded from thermoplastic material such as, for example,acrylic or butyrate resin, and adapted for a close fit with each oftheir respective channel-shaped arms. Tongues 50 on the forward end ofthe Q associated with the white key pieces to thereby anchor the forwardend of the white key pieces.

The electrical circuit assembly shown generally at FIG. 6 includes aplurality of circuit making contacts adapted to be operated inconjunction with manual operation of individual key assemblies, isdisposed below longitudinally extending horizontal channel portion 20.An insulating board 51 extends the entire length of the keyboard chassisand is supported immediately below chassis portion by a plurality ofrubber or neoprene grommets 52. As shown in detail in FIG. 6, insulatingboard 51 has disposed on the top surface thereof a plated or etchedcircuit pattern of a predetermined configuration. A plurality of flatinsulating members 54, having enlarged threaded portions 55, are securedby screws 56 to extend vertically below and transverse to thelongitudinal dimension of insulating panel 51. A plurality of buss barsor signal mixing busses 57 are supported by insulating member 54 a shortdistance below the bottom surface of panel 51 and extend the entirelength of the panel.

Flexible, tightly wound coil springs 58 are secured at one end byinsulating panel 51. The free end of springs '58 extend perpendicularlydownward from panel 51. As

shown in FIGS. 2 and 5, several such coil springs are disposedtransverse to the longitudinal direction insulating panel 51, generallybelow each key assembly and offset a short distance from buss bars 57.In addition, there is one coil spring in the longitudinal direction ofpanel 51 for each key assembly to thereby form a plurality oftransversely speced longitudinally extending rows. Coil springs 58 arepreferably closely wound from small diameter Phosphor bronze wire forflexibility, and are gold clad for increased electrical conductivity andlow contact potential. The free ends of each set of transversely spacedcoil springs are physically connected together by insulating member 60.A plurality of holes, undersized with respect to the diameter of thecoil springs 58, provide a secure mechanical bond between insulatingmember 60 and coil springs 58.

A tie-bar portion 61 substantially reduced in diameter and integral withinsulating member 60, is joined to locking portion 62, adapted toprovide an interlocking coupling with lever arm 70. As best shown inFIG. 4, generally V-shaped keyway 65 opens into a circular apex toprovide an interlocking coupling with locking portion 62. In analternate embodiment shown in FIG. 7, tie bar portion 61 of insulatingmember 60 is integrally joined with a flat disc-shaped portion 63 havingaperture 64 therein, which aperture maybe conveniently interlocked witha mating pin member on the lower portion of lever means 70. To this endmodified lever means 170 (FIG. 8) has a dimpled dowel member 165 locatedon the bottom portion thereof. Lever means 170 has a molded plastic orrubber cap 172 secured to a generally circular top portion .to providesound deadening when engaging the key assembly. Insulating member 60,along with tiebar portion 61 and the locking portion is preferablymolded as an integral unit from a relatively flexible plastic materialsuch as polyethylene, polyvinyl chloride, or neoprene rubber.

There is one lever means 70 associated with each key assembly,interlocked with each insulating member 60 so as to provide mechanicalcoupling with a corresponding set of coil springs. Lever means 70includes an offset, generally horizontal portion 71 having a slottherein adapted to receive sound deadening material 72 such as felt or apliable plastic material. Chassis portion 20 has a plurality of openingsnear the front marginal edge thereof to allow one arm of lever means 70to extend downwardly for interlocking coupling with the tie-bar providedby insulating member 60. As best illustrated in FIG. 4, a longitudinallyextending rod 73, secured to chassis portion 20 by brackets 75, extendsthrough the pivotal points of lever means 70. Horizontally extendingoff-center portion 71 of the upper arm of lever means 70 is of such awidth and height to fit within channel-shaped arms 14a and 1412 withoutmaking physical contact with side portions 32. A small nominal clearancemay be provided between sound deadening material 72 and the upperportion of channels 14a and 14b.

As shown in FIG. 5, wherein a key assembly is illustrated in its-extremedownward portion in abutment with stop member 37, a bearing surface isprovided between the top inner surface of channel-shaped arm 14b andsound deadening material 72. Since this hearing point is horizontallydisposed in a position which is off-center with respect to its pivotalpoint, lever means pivots about rod 73, causing its lower arm to moveforward to provide a forward translational motion to insulating member60. The lower portion of the springs 58, positioned on the opposite sideof the mixing busses, are imparted with a like translational movement.Tie-bar portion 61 of insulating member 60 is flexed when the rotationof lever means 70 causes the lower extending arm to move in an arcuatepath to compensate for the vertical component of such movement. Suchflexing allows the free ends of springs 58 to be translated in asubstantially horizontal plane so that portions of the springs adjacentto mixing busses 57 make firm, positive contact without a sliding orrubbing action and without any vertical extension of the springs. Thiseliminates arcing and contact wear to insure noiseless switching andlong operating life. Upon release of the key assemblies they are biasedto their normal upward position and springs 58 return to their verticalposition to break the electrical contact. Because of the flexiblecoupling provided by tie-bar portion 61 of insulating member 60, thesprings 58 are translated in the same plane as the circuit-makingswitching action. Thus, quick-acting, noiseless circuit making andcircuit breaking is provided with a minimum of manual keyboard pressure.Further, because of the flexibility of the coil springs and of thetie-bar coupling, it is not necessary that individual groups of coilsprings 58 and associated insulating members 60 be in exact transversealignment with the plane of rotation of lever means 70, or be locatedimmediately below individual key assemblies. This allows ease ofassembly of the unit and interchangeability of parts without requiringclose structural tolerances. Proper switching action is obtained eventhough panel 51 and the coil springs located thereon may varylongitudinally with respect to the key assemblies.

As best seen from FIG. 3, three mixing busses are disposed parallel toone another and are supported by insulating members 54 to extend alongthe length of panel 51. Grommets 52 are regularly spaced along thelength of the panel and engage chassis portion 20 to provide a cushionedmounting between the panel and the chassis. Because of the extensivelongitudinal dimensions of panel 51 and chassis 10 and because of theirrelative differ ences in temperature coefficients of expansion, grommets52 are preferably rubber or a similar flexible material. This allowsthermal expansion of panel 51 relative to chassis 10 without crackingand buckling.

Of the three mixing busses shown, two are illustrated as small diametermetal rods having sufficient rigidity to function as fixed contacts forthe switching arrangement described. Preferably they are clad with ahighly conductive metal such as gold to increase conductivity and toreduce contact resistance. The third mixing buss is shown with a coatingof insulating material 59. This material may be vinyl plastic or siliconrubber, impregnated with graphite or carbon, to provide a given amountof resistivity between the springs and the mixing busses. Thisresistivity may range from zero ohms to a selected high value, or may bevariable with contact pressure to provide a degree of volume control asthe manual pressure applied to the key assemblies is varied. Theresilience of such material provides additional noise deadening duringswitching. It is to be understood from the foregoing that any number ofmixing busses may be employed as the fixed switch contacts, and mayutilize various combinations of the mentioned structural feationsillustrated.

' 7 The top surface of insulating panel 51, with a representative platedor etched circuit pattern disposed there on, is shown in FIG. 6.Conductors 80 interconnect a plurality of plated or etched eyelets andfeedthrough apertures of the type commonly employed in printed cir-.through soldered to selective ones of the eyelets and associatedinterconnecting conductors 80. For the threebuss panel shown, conductors80 provide octave-to-octave coupling for three octaves. However, tolesser or greater degrees, circuit intercoupling and signal mixing ofselective tone generators can be achieved to provide a desirable musicaleffect by selection of other plated or etched circuit patterns andresistor interconnections.

While the invention has been described more or less precisely as todetails of construction, it is to be understood that modifications andvariations of the novel features disclosed may be achieved by thoseskilled in the art without departing from theispirit and scope of theinvention set forth in the appended claims.

I claim: a

1. A key switch assembly for use in an electronic organ including incombination, a substantially horizontally disposed keyboard chassis,said chassis including a plurality of elongated key assemblies supportedfor pivotal movement in a vertical direction, a plurality of lever meanspivotally mounted on said chassis and individually connected to said keyassemblies so that operation of .a key causes arcuate movement of theassociated lever means in a vertical plane, an insulating panelsupported by said chassis and having a plurality of circuit conductorsdisposed thereon, a plurality of fixed signal conductors insulatinglysupported in spaced relationship with respect to said panel, a pluralityof elongated coil springs each having first and second substantiallycoaxial ends and intermediate portions between said ends, said firstends of said coil springs being supported on said panel and electricallyjoined with selected ones of said circuit conductors, said intermediateportions of said coil springs extending normal to said panel and inclose proximity to said signal conductors, and a plurality of insulatingmembers joining said second ends of said coil springs with said levermeans, said insulating members each having an elongated body portionfixedly secured to said second ends of selected coil springs, a flexibleportion extending from said body portion, and a connecting portionsecuring said flexible portion to said lever means, whereby arcuatemovement of said lever means is transmitted through said flexibleportions of said insulating members to provide translational movement ofsaid body portions thereof which is imparted to said second ends of saidcoil springs to stretch said coil springs about said signal conductorsand thereby bring said coil springs into positive contact with saidsignal conductors.

2. A key switch assembly for electronic organs including in combination,a substantially horizontally disposed keyboard chassis, said chassisincluding a plurality of elongated key assemblies pivotally supportednear one end for movement in a vertical direction, a plurality of levermeans having arms extending vertically above and below a fulcrum pointat the horizontal surface of said chassis, with each said lever meansadapted to coact with individual key assemblies for arcuate movement ina vertical plane, an insulating panel having a plurality of etchedcircuit conductors disposed on one major surface thereof mountedparallel to and below said chassis, a plurality of fixed sig- 8 nalmixing busses insulatingly supported in spaced relationship from theother major surface of said panel, a plurality of elongated coil springseach having first and second substantially coaxial ends,said coilsprings extending normal to said other major surface in close proximityto said mixing busses, with said first end of said coil springsprojecting through apertures in said panel and electrically joined withselected ones of said etched circuit conductors, and a plurality ofhorizontally disposed insulating members joining said second ends ofselected coil springs with the. downwardly extending arms of said levermeans, said insulating members each havinga first portion withvertically disposed apertures therein to fixedly receive said secondends of selected coil springs, a second portion to provide lockingengagement with the downwardly extending arms of said lever means, and aflexible 7 intermediate portion of reduced cross-section forming atie-rod to link said first portion and said lever arm engaging portion,whereby arcuate movement of said lever arms imparts translationalmovement to said second ends of said coil springs to thereby bring theminto positive contact with said mixing busses.

3. A key switch assembly including in combination, a substantiallyhorizontally disposed keyboard chassis, said chassis including aplurality of elongated key assemblies pivotally supported near one endfor movement in a vertical direction, a plurality of lever means havingarms extending vertically above and below a fulcrum point at thehorizontal surface of said chassis, with each said lever means adaptedto coact with individual key assemblies for arcuate movement in avertical plane, an insulating panel having a plurality of plated circuitconductors disposed on one major surface thereof mounted parallel to andbelow said chassis, a plurality of horizontally disposed buss barsinsulatingly supported from the other major surface of said panel, withat least one of said buss bars having 'a coating of flexible carboncontaining material, a plurality of elongated coil springs extendingperpendicular to said panel in close proximity to said buss bars, withone end of said coil springs extending through apertures in said paneland electrically joined with selected ones of said plated circuitconductors, and a plurality of horizontally disposed insulating membersjoining the other end of said coil springs with the downwardly extendingarms of said lever means, said insulating members having a first portionwith vertically disposed apertures therein to receive said other ends ofselected ones of said coil springs, a second portion to provide lockingengagement with the downwardly extending arms of said lever means, and aflexible intermediate portion of reduced cross-section forming a tie rodbetween said first port-ion and said lever arm engaging portion, wherebyarcuate movement of said lever arms imparts translational movement tosaid other ends of said coil springs to thereby complete an electricalcircuit between said contact members and said plated circuit conductors.

4. A key switch assemblyfor electronic musical instruments including incombination, a keyboard and chassis having a substantially flathorizontally disposed portion, said chassis including a plurality ofelongated key assemblies pivotally supported near one end for movementin a vertical direction, .a plurality of lever means having a fulcrumpoint in the plane of the horizontal portion of said chassis means, eachsaid lever means having a first arm extending vertically below thehorizontal surface of said chassis and a second arm extending verticallyabove the horizontal surface of said chassis, with said second armhaving a horizontally extending portion containing a v e ticallyextending noise deadening member adapted to coact with individual onesof said key assemblies for arcuate movement in a vertical plane, aninsulating panel having a plurality of plated circuit conductorsdisposed on one major surface thereof and mounted parallel to and belowthe horizontal portion of said chassis, a plu rality of buss barsinsulatingly supported in spaced relationship with respect to the othermajor surface of said panel, a plurality of elongated coil springs eachhaving first and second ends, said coil springs extending normal to saidother major surface in close proximity to said buss bars, with saidfirst ends of said coil springs extending through apertures in saidpanel and electrically joined with selected ones of said plated circuitconductors, and a plurality of insulating members each having aresilient portion forming a tie bar for flexible coupling between saiddownwardly extending lever arms and the other ends of selected coilsprings, each of said insulating members hav ing a first body portionfixedly secured to said second ends of selected coil springs, a secondconnecting portion secured to one of said lever arms, and a flexibleintermediate portion joining said first and second portions, so that vertical depression of said key assemblies imparts horizontal translationalmovement to said others ends of said coil springs, said coil springsbeing pulled and stretched across said buss bars to thereby complete anelectrical circuit between said contact members and said buss bars.

5. A key switch assembly including in combination, a substantiallyhorizontally disposed keyboard chassis, said chassis including aplurality of elongated key assemblies pivotally supported near one endfor movement in a vertical direction, said key assemblies including anelongated channel-shaped arm having a flanged portion adapted to engagefingers upstanding on the front marginal edge of said chassis to limitthe vertical movement of said key assemblies, a plurality of lever meanshaving a fulcrum point near the front marginal edge of said chassis,

said lever means each having a first arm extending vertically below thehorizontal surface of said chassis and a second arm extending verticallyabove the horizontal surface of said chassis, with said second lever armhaving a horizontally extending portion containing noise deadeningmaterial adapted to engage said channel-shaped arm and to coact withsaid key assembly for arcuate movement in a vertical plane, aninsulating panel having a plurality of plated circuit conductorsdisposed on one major surface thereof mounted parallel to and below saidchassis, a plurality of fixed electrical contact members insulatinglysupported from the other major surface of said panel, a plurality ofelongated coil springs extending perpendicular to said other majorsurface in close proximity to said contact members, with one end of saidcoil springs extending through apertures in said panel to makeelectrical contact with selected ones of said plated circuit conductors,and a plurality of insulating members each having a resilient portionforming a tie-bar to provide flexible coupling between said second leverarms and the other end of selected coil springs, each of said insulatingmembers having a first body portion fixedly secured to said other endsof selected coil springs, a second portion mechanically connected to oneof said lever arms, and a flexible intermediate portion of reducedcross-section connecting said first and second portions, so thatvertical depression ofv said key assemblies imparts horizontaltranslational movement to the free ends of said coil springs to therebycomplete an electrical circuit between said contact members and saidplated circuit conductors.

6. A keyboard assembly including in combination, a generally elongatedchassis, said chassis including a horizontal panel section having aseries of upwardly projecting longitudinally spaced front keypositioning fingers and rear fulcrum forming means, a set oftransversely extending longitudinally spaced key assemblies movablysupported on said chassis and forming a keyboard, the rear end portionof each key assembly being pivotally mounted on said fulcrum formingmeans and the front end portion thereof engaging saidfront keypositioning fingers, a plurality of levers pivotally secured to saidhorizontal panel section, each said lever having an arm extending belowsaid horizontal panel section and an arm extending above said horizontalpanel section, with the upwardly extending arm of each said levercoacting with individual ones of said key assemblies for arcuatemovement in a vertical plane, a flat elongated insulating panel mountedwith the major surfaces thereof parallel to and below said horizontalpanel section, a plurality of signal mixing busses insullatinglysupported in spaced relationship with respect to one major surface ofsaid insulating panel, a plurality of elongated resilient coil springsextending vertically from said insulating panel in close proximity tosaid signal mixing busses, with one end of each said coil springssecured in fixed position by said insulating panel, and a plurality ofinsulating members each having a resilient portion forming a tie barflexibly coupling the other end of selected coil springs to thedownwardly extending arm of a coacting lever, said insulating memberseach having a body portion fixedly secured to said other ends of saidselected coil springs, a flexible portion extending from said bodyportion and a connecting portion securing said flexible portion to saidarm of one of said levers, whereby arcuate movement of said leversimparts translational movement to said other ends of selected coilsprings to thereby make positive electrical contact with said mixingbusses.

7. For use with a keyboard having a plurality of key assemblies adaptedto coact with lever means to impart arcuate movement thereto, thecombination including a flat elongated insulating panel having first andsecond major surfaces, a plurality of elongated buss bars insulatinglysupported at fixed points from said first major surface, a platedcircuit pattern including a plurality of conductors and terminal areasdisposed on said second major surface, a plurality of apertures of afirst size extending between said major surfaces opening into selectedportions of said plated circuit pattern, a plurality of apertures of asecond size extending to said major surfaces opening into areas notcovered by said plated circuit pattern, a plurality of electricalresistors disposed on said first surface having leads extending throughselected apertures of said first size and electrically joined to saidcircuit pattern, a plurality of flexible grommets engaging'saidapertures of said second size for suspending said panel from saidkeyboard, a plurality of elongated coil springs disposed perpendicularto said first major surface extending in close proximity to said bussbars, said coil springs having one end engaging selected apertures ofsaid first size and in electrical contact with said plated circuitconductors, and a plurality of insulating members each engaging theother ends of selected coil springs, each said insulating member havinga resilient elongated tie rod formed as an integral part therewith, withsaid tie rods adapted to provide a flexible linkage between saidselected coil springs and corresponding lever means.

8. A keyboard assembly including in combination, a generally elongatedchassis means, said chassis means -including a horizontal panel sectionhaving a series of upwardly projecting longitudinally spaced frontkey-positioning fingers and rear fulcrum-forming means, a set oftransversely extending longitudinally spaced key assemblies m-ovablysupported upon said chassis means and forming a keyboard, the rear endportion of each key assembly being pivotally mounted upon saidfulcrum-forming means and the front end portion thereof engaging saidfront key-positioning fingers, with said key assemblies having meanscoacting with said front key positioning fingers to limit the verticalmovement thereof, a set of lever means secured to said horizontal panelsection, each said lever means having an arm extending below saidhorizontalpanel section and an arm extending above said horizontal panelsection, with the upwardly extending arm of each said lever meanscoacting with individual ones of said key assemblies for arcuatemovement in a vertical plane, a generally flat insulating member mountedwith the major surfaces thereof parallel to and below said horizontalpanel section, a plurality of fixed electrical contacts insulatinglysupported from one major surface of said insulating board, a pluralityof elongated resilient coil springs extending vertically from saidinsulating board 1 1 in close proximity to said fixed contacts, with oneend of each said coil springs secured in fixed position by saidinsulating board, and a plurality of resilient insulating member formingtie bars connecting the other end of selected ones of said coil springsto coact with downwardly extending lever arms of corresponding levermeans, each of said resilient insulating members including a first bodyportion fixedly secured to said other ends of said selected coilsprings, a second portion mechanically connected to one of said levermeans, and a flexible intermediate portion of reduced cross-sectionconnecting said first and second portions.

References Cited by the Examiner UNITED STATES PATENTS Roe 200-86.5 XBozak et al. 84-1.01, Larsen et al.. 2001 8 Enochs et a1. 84-423 Mann84--1.01 Cutler et a1 200153 Kohler 317-401 Henss 317-101 DAVID J.GALVIN, Primary Examiner.

6. A KEYBOARD ASSEMBLY INCLUDING IN COMBINATION, A GENERALLY ELONGATEDCHASSIS, SAID CHASSIS INCLUDING A HORIZONTAL PANEL SECTION HAVING ASERIES OF UPWARDLY PROJECTING LONGITUDINALLY SPACED FROM KEY POSITIONINGFINGERS AND REAR FULCRUM FORMING MEANS, A SET OF TRANSVERSELY EXTENDINGLONGITUDINALLY SPACED KEY ASSEMBLIES MOVABLY SUPPORTED ON SAID CHASSISAND FORMING A KEYBOARD, THE REAR END PORTION OF EACH KEY ASSEMBLY BEINGPIVOTALLY MOUNTED ON SAID FULCRUM FORMING MEANS AND THE FRONT ENDPORTION THEREOF ENGAGING SAID FRONT KEY POSITIONING FINGERS, A PLURALITYOF LEVERS PIVOTALLY SECURED TO SAID HORIZONTAL PANEL SECTION, EACH SAIDLEVER HAVING AN ARM EXTENDING BELOW SAID HORIZONTAL PANEL SECTION AND ANARM EXTENDING ABOVE SAID HORIZONTAL PANEL SECTION, WITH THE UPWARDLYEXTENDING ARM OF EACH SAID LEVER COACTING WITH INDIVIDUAL ONES OF SAIDKEY ASSEMBLIES FOR ARCUATE MOVEMENT IN A VERTICAL PLANE, A FLATELONGATED INSULATING PANEL MOUNTED WITH THE MAJOR SURFACES THEREOFPARALLEL TO AND BELOW SAID HORIZONTAL PANEL SECTION, A PLURALITY OFSIGNAL MIXING BUSSES INSULLATINGLY SUPPORTED IN SPACED RELATIONSHIP WITHRESPECT TO ONE MAJOR SURFACE OF SAID INSULATING PANEL, A PLURALITY OFELONGATED RESILIENT COIL SPRING EXTENDING VERTICALLY FROM SAIDINSULATING PANEL IN CLOSE PROXIMITY TO SAID SIGNAL MIXING BUSSES, WITHONE END OF EACH SAID COIL SPRINGS SECURED IN FIXED POSITION BY SAIDINSULATING PANEL, AND A PLURALITY OF INSULATING MEMBERS EACH HAVING ARESILIENT PORTION FORMING A TIE BAR FLEXIBLY COUPLING THE OTHER END OFSELECTED COIL SPRINGS TO THE DOWNWARDLY EXTENDING ARM OF A COACTINGLEVER, SAID INSULATING MEMBERS EACH HAVING A BODY PORTION FIXEDLYSECURED TO SAID OTHER ENDS OF SAID SELECTED COIL SPRINGS, A FLEXIBLEPORTION EXTENDING FROM SAID BODY PORTION AND A CONNECTING PORTIONSECURING SAID FLEXIBLE PORTION TO SAID ARM OF ONE OF SAID LEVERS,WHEREBY ARCUATE MOVEMENT OF SAID LEVERS IMPARTS TRANSLATIONAL MOVEMENTTO SAID OTHER ENDS OF SELECTED COIL SPRINGS TO THEREBY MAKE POSITIVEELECTRICAL CONTACT WITH SAID MIXING BUSSES.